Intravascular catheter with guiding structure

ABSTRACT

Intravascular catheters that include a flexible catheter body, a distal housing secured to the catheter body, a work element disposed within the housing and exposed to the external environment through a side window, and a guiding structure for the work element, are disclosed. An axial path through the housing is defined by the guiding structure. Embodiments of the guiding structure include a slot or channel formed in the housing, a coaxial tube attached to the housing, a radially offset ribbon attached to the housing, or the external surface of the housing itself. The work element, such as a rotatable cutting blade in an atherectomy catheter, is coupled to the guiding structure such that the work element is retained within the housing during insertion and operation of the catheter and even when the housing is bent or distorted as a result of bends in the blood vessel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to the construction and use ofvascular catheters. More particularly, the invention relates tointravascular catheters having a work element within a distal housing,and a work element guiding structure.

2. Previous Art

Arteriosclerosis, also known as atherosclerosis, is a diseasecharacterized by the deposition of a fat-like substances, referred to asatheroma or plaque, on the walls of blood vessels. Such deposits canoccur both in peripheral blood vessels that feed the limbs of the bodyand in coronary blood vessels that feed the heart. When depositsaccumulate in localized regions of a blood vessel, the regions become"stenosed"; blood flow is restricted and the person's health is atserious risk.

Numerous approaches for restoring blood flow by reducing and removingstenotic deposits have been proposed. Balloon angioplasty, for example,uses a balloon-tipped catheter to dilate the stenosed region.Atherectomy procedures use a blade or other cutting element to sever andremove stenotic material. Laser angioplasty directs laser energy toablate at least a portion of the stenotic material.

Of particular interest are atherectomy catheters in which a cuttingblade advances past an opening at the distal end of a vascular catheter.The catheter exposes the opening to at least a portion of the stenoticmaterial. The stenotic material extends through the opening where thecutting blade advances and severs the stenotic material. Typically, suchcutting blades are circular and are rotated (or rotationally oscillated)and advanced simultaneously to effect the desired cutting.

Although such atherectomy catheters have enjoyed widespread success inboth peripheral and coronary applications, certain design limitationspersist. In small diameter catheters used in the coronary arteries, forexample, very tight vascular bends are encountered. Typically, aguidewire is first inserted through the blood vessel and advanced alongthe lumen of the vessel until proximate to the stenosed region. Thecatheter slides over, and along, the guidewire until the catheterpositions adjacent a stensosed region. Atherectomy catheters havingrigid housings at their distal ends have difficulty inserting past tightvascular bends. The rigidity of the housing causes lateral displacementof the guidewire. Difficulties associated with guide wire movement andtight vascular bends are exacerbated by elongated housings whichfrequently collect severed stenotic material in a forward nosecone.

In an effort to enhance the maneuverability within the tortuous regionsof the coronary arteries, atherectomy catheters having flexible cutterhousings have been employed. Commonly assigned flexible housings takevarious forms, including a braid-reinforced polymeric structure and aslotted metal tubular structure.

Although flexible housings offer a significant improvement overcomparably sized rigid cutter housings when employed in coronaryarteries and other tortuous regions of the vascular system, they dopresent limitations. In particular, bending and flexing of the flexiblehousings inhibits axial advancement of the cutting blades within thehousing. Also, bending of the housing sometimes causes an advancingcutting blade to undesirably extend outward from the window. Outwardextension of the cutting blade may render the cutting blade inoperableor interfere with the housing and the guidewire. Such consequencesprevent proper operation of the catheter by distorting the housing.Outwardly extending cutting blades are unwieldy and generallyundesirable.

Efforts to overcome undesired extension of cutting blades continue.Reducing the width of the housing window prevents extension of thecutting blades. This modification, however, reduces the amount ofstenotic material which can be removed in a single pass of the cuttingblade through the housing.

Various related efforts manifest themselves in atherectomy cathetersdescribed in U.S. Pat. No. 4,926,858, issued May 22, 1990 to Gifford,III et al. entitled "ATHERECTOMY DEVICE FOR SEVERE OCCLUSIONS"; U.S.Pat. No. 4,979,951, issued Dec. 25, 1990, to Simpson, entitled"ATHERECTOMY DEVICE AND METHOD"; U.S. Pat. No. 5,047,040, issued Sep.10, 1991, to Simpson et al. entitled "ATHERECTOMY DEVICE AND METHOD";U.S. Pat. No. 5,084,010, issued Jan. 28, 1992, to Plaia et al., entitled"SYSTEM AND METHOD FOR CATHETER CONSTRUCTION"; and Re. U.S. Pat. No.33,569, issued Apr. 9, 1991, to Gifford III et al. entitled "SINGLELUMEN ATHERECTOMY CATHETER DEVICE". Of these, the U.S. Pat. Nos.4,979,951 and Re. 33,569 patents describe catheters having distalhousings in which a rotatable cutting blade receives a coaxial movableguidewire. Moveable guidewires generally do not securely hold thecutting blade within the housing. Additionally, in some devices, theguidewire itself may be severed by the cutting blade. Copending U.S.Pat. No. 5,250,059, issued Oct. 5, 1993 to Andreas et al., entitled"ATHERECTOMY CATHETER HAVING FLEXIBLE NOSE CONE" is commonly assigned tothe assignee of the present application, and describes an atherectomycatheter having a flexible nose cone attached to the distal end of acutter housing. A rotatable cutting blade is optionally received over amovable guidewire which passes through the nose cone, the housing andthe cutting blade drive (torque) cable.

Placement of the cutting blade of an atherectomy catheter over aconventional movable guidewire has been proposed (See, U.S. Pat. Nos.4,669,469, and Re. 33,569). Conventional guidewires could restrain thecutting blade within the cutter housing under some circumstances.Unfortunately, the guidewire itself will often be displaced as theatherectomy catheter is advanced over the guidewire.

Guidewire movement is due to the fine gauge (usually 0.007 inch) of theguide wire. Furthermore, since the guidewire is not fixed at its distalend, it does not necessarily conform to the specific distortions of thehousing within a contorted blood vessel, and thus is not alwaysefficient in guiding the cutter as it is advanced within the housing.Thus, movable guidewires cannot be relied on to cooperate with anaxially translatable cutter within the cutter housing under allcircumstances.

Improved intravascular catheters are desired. In particular, it isdesirable to provide a way of retaining a cutting blade (work element)within the housing of a catheter. It is desirable to provide a flexiblehousing in which the cutting blade will not interfere with the guidewireor the housing of the catheter. It is desirable to provide a way ofretaining the cutting blade which is compatible with housings of varioussizes and configurations.

SUMMARY AND OBJECTS OF THE INVENTION

The various objects of the invention which are presented and which willbecome apparent below are presented by way of example only and are notintended to limit the scope of the present invention. The presentinvention is to be limited only by the claims.

It is an object of this invention to provide intravascular catheterssuitable for operation in blood vessels with tight bends.

It is a further object of this invention to provide intravascularcatheters with work elements that are retained within flexible distalhousings during insertion and operation of the catheter.

It is a further object of this invention to provide intravascularcatheters with a work element that follows the longitudinal path of thehousing during axial translation of the work element.

It is a further object of this invention to provide methods of usingintravascular catheters with guiding structures in intravascularsurgical interventions.

It is a further object of this invention to provide methods of usingatherectomy catheters with guiding structures to perform coronaryatherectomies.

In accordance with the above objects and those that will be mentionedand will become apparent below, the intravascular catheter of thepresent invention comprises:

a catheter body having a proximal end, a distal end and a lumentherebetween;

a housing with a cylindrical body, a longitudinal axis, an internalsurface, an external surface, a window on a lateral side thereof, and anopen proximal end secured to the distal end of the catheter body, thehousing defining a hollow interior;

a work element disposed within the housing and having a proximal end;

a cable substantially disposed within the lumen of the catheter body,the connector having a proximal end and a distal end and the distal endbeing connected to the proximal end of the work element;

a guiding structure affixed to the housing and slidably connected to thework element, the guiding structure defining a fixed axial path relativeto the housing,

whereby the work element is retained within the housing during insertionof the catheter within a blood vessel and during axial translation ofthe work element along the axial path of the guiding structure.

The catheters of the embodiments of the present invention all include aguiding structure affixed to or incorporated into the housing andslidably connected to the work element. The catheters also have otheradditional features in common. These include a long flexible catheterbody with a housing attached to the distal end. The housing has anopening along a lateral side. The work element is disposed within thehousing. A cable is attached to the work element. The connector goesfrom the work element, through the catheter body and out its proximalend. The work element within the housing is operated from the proximalend of the catheter body via the cable.

In an embodiment of the invention, the guiding member includes at leasttwo longitudinal slots through the internal surface of the housing. Aslider is attached to the work element and has pins projecting radiallythat are positioned within each slot and able to slide along the slot asthe work element is moved back and forth. The angle between the pinsinsures that the pins remain in their slots and this insures that thework element stays within the housing and follows the axial path of thehousing even when the housing is bent.

In another embodiment, a single longitudinal slot is provided along thehousing. This slot is substantially a tunnel within the body of thehousing and communicates with the hollow interior of the housing througha narrow axial neck. A slidable pin conforming to the shape of the slotis positioned within the slot and attached to a slider which in turn isattached to the work element, thereby registering the axial path of thework element to the housing.

In an additional embodiment, the guiding member is a longitudinal shaft,sometimes tubular and sometimes ribbon shaped, usually flexible. Theshaft is positioned within the hollow interior of the housing andattached to the housing. The shaft passes through a tunnel attached toor within the work element such that the work element is slidable alongthe shaft.

In a particular configuration of this embodiment, the shaft is coaxialwith the longitudinal axis of the housing and the tunnel is in thecenter of the work element, permitting the work element to rotate aboutthe shaft.

In yet another embodiment, the guiding member includes the exteriorsurface of the housing, and a band is coupled to the work element andcircumscribes the exterior surface of the housing. The band slides alongwith the work element and keeps the work element inside of the housing.

According to an embodiment of the method of the present invention, anintravascular catheter as described herein is provided. The catheter isinserted into the lumen of a blood vessel starting from the distal endof the catheter. The catheter is advanced until the housing is adjacentto a site of interest, e.g. stenotic material within a blood vessel. Thework element is then operated in a manner specific to the function ofthe work element. The path of axial movement of the work element withinthe housing is registered to the axial path provided by the guidingmember.

The intravascular catheter of the present invention can be fitted with avariety of work elements each performing a specific task. The cable ischosen to complement the function of the work element. For example, whenthe work element is a cutting blade, the cable is rotated, which in turnrotates the cutting blade. The cable is translated axially to advancethe cutting blade past the lateral window of the housing, wherebystenotic material extending through the window into the hollow interiorof the housing is severed.

It is to be understood that the intravascular catheter of the presentinvention is conceived to operate with a variety of work elements andcorresponding connectors that differ in the interventional task thateach is designed to perform. A wide variety of work elements (andcables) are known to those skilled in the art, e.g. cutting blades (andcables) for performing atherectomy procedures, heated elements(electrical wires) for performing thermal ablation, electrodes(electrical wires) for performing electrosurgical cutting andcauterization, abrasive elements for performing mechanical ablation(cables), optical waveguides (fiber optic lines) for performing laserablation, ultrasonic transducers (ultrasonic transduction lines) forimaging and ablation, angioscopic imaging devices (fiber optic lines)and the like. The present invention is particularly useful for workelements requiring axial translation during operation.

It is an advantage of the intravascular catheters of the instantinvention to be operable in blood vessels with tight bends, e.g.coronary arteries.

It is a further advantage of the catheters of this invention to becompatible with flexible housings and to be operable when the housing isbent or distorted.

It is an additional advantage of the catheters of this invention to havework elements whose axial translational path is registered to the axialpath within the housing.

It is a further advantage of the catheters of this invention that escapeof the work element through the window on a lateral side of the housingis minimized.

It is yet another advantage of this invention to be able to use housingswith wide windows while retaining the work element within the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the objects and advantages of the presentinvention, reference should be had to the following detaileddescription, taken in conjunction with the accompanying drawing, inwhich like parts are given like reference numerals and wherein:

FIG. 1 is a side elevational view of an intravascular atherectomycatheter with the work guiding structure of the present invention.

FIG. 2 is a cross-sectional view along line 2--2 of FIG. 1 looking inthe direction of the arrows.

FIG. 3 is a detailed side view of an atherectomy cutter housing.

FIG. 4 is a partial cross-sectional view of the cutting blade and slidershown in FIG. 3.

FIG. 5 is a cross-sectional view of FIG. 3 taken along line 5--5 lookingin the direction of the arrows.

FIG. 6 is a cross-sectional view of FIG. 3 taken along line 6--6 lookingin the direction of the arrows.

FIG. 7 is a cross-sectional view of FIG. 4 taken along line 7--7 lookingin the direction of the arrows.

FIG. 8 is a cross-sectional view illustrating another embodiment of theguiding structure.

FIG. 9 is a partial sectional view of FIG. 8 taken along the line 9--9looking in the direction of the arrows.

FIG. 10 is a cross-sectional side view of an additional embodiment ofthe guiding structure.

FIGS. 11 and 12 illustrate the operation of the atherectomy device ofFIG. 10 in severing stenotic material from a blood vessel.

FIG. 13 is a cross-sectional view of a preferred embodiment of theguiding structure of the present invention.

FIG. 14 is a cross-sectional view of FIG. 13 as seen along line 14--14looking in the direction of the arrows.

FIG. 15 is a side view illustrating a further embodiment of the guidingstructure of the present invention.

FIG. 16 is a side view illustrating a detail of the guiding structureshown in FIG. 15.

FIG. 17 is a cross-sectional view of FIG. 15 taken along line 17--17looking in the direction of the arrows.

FIG. 18 is a cross-sectional view of FIG. 15 taken along line 18--18looking in the direction of the arrows.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides intravascular catheters with guidingstructures 100. The catheters include an elongated flexible catheterbody and a housing secured to the distal end of the catheter body. Thehousing holds the work element adjacent to an elongated window. Thewindow is located on a lateral side of the housing. A cable extendsthrough a lumen of the catheter body and attaches to the work element.The cable operates the work element within the housing.

The invention features guidance and retention structures for the workelement within the housing. Particularly, the invention provides aguiding member that retains the work element within the housing,prevents escape of the work element through the window of the housing,and guides the axial translation of the work element along thelongitudinal axis of the housing. The work element is thus containedwhen very wide windows are provided in the housing or when the housingis flexible and subjected to bending, deformation or distortion whichmight otherwise cause the work element to be lost from the housing.

The present invention is useful with a wide variety of catheters havingvirtually any type of axially translatable work element. The presentinvention is especially useful in atherectomy applications where thework element is a rotating or rotationally oscillating cutting blade andis operated by simultaneously rotating and axially advancing the bladepast the side window in the housing in order to sever and removestenotic material from an area of interest, e.g. a stenosed region ofblood vessel. Such atherectomy devices and procedures are described inU.S. Pat. Nos. 4,669,469; 4,926,858; 4,979,951; 5,047,040; 5,084,010;and Re. 33,569, the full disclosures of which are incorporated herein byreference.

Preferred embodiments of the present invention are cathetersparticularly adapted to perform atherectomies. Consequently, in severalembodiments the work element is referred to as a "cutting blade" and thecable is referred to as a "cable". It is to be understood, however, thatthe work guiding structure 100s of the present invention can be usedwith many other catheter types, all of which are within the intendedscope of this invention.

Referring now to the drawings, a number of exemplary embodiments ofcatheters employing work element guide systems constructed in accordancewith the principles of the present invention will be described. It willbe appreciated, however, that these embodiments are merely exemplary andthat a wide variety of other specific implementations are within thescope of the present invention.

Referring now to FIGS. 1 and 2, FIG. 1 shows a side view of anintravascular catheter generally indicated by the reference numeral 110.FIG. 2 is cross-sectional view of the catheter body 112 of FIG. 1 asseen along the line 2--2 in the direction of the arrows. The catheterbody 112 includes a housing 140 with a window 142, a work element 138,and a cable 134.

With particular reference to FIG. 1, there is shown the catheter body112 which has a proximal end 114, a distal end 116 and at least oneinternal lumen 133 (FIG. 2). The housing 140 includes a distal end 141and a proximal end 139. A hollow nose cone 144 attaches to and coversthe distal end 141 of the housing 140. The distal end 116 of thecatheter body 112 attaches to the proximal end 139 of the housing 140.The lumen 133 of the catheter body 112 holds the cable 134.

The housing 140 is a hollow cylinder having an axis 137, an innersurface 108, an outer surface 109, and a window 142. The proximal end139 and distal end 141 of the housing 140 are open to establishcommunication between the catheter body 112 and the nose cone 144.

A balloon 126 attaches on the outer surface 109 of the housing 140 onthe side opposite from the window 142. The balloon 126 communicates witha balloon inflation lumen 135 within the catheter body 112 (FIG. 2). Theballoon is inflated after the catheter 110 is positioned within a bloodvessel. When the balloon 126 inflates, the balloon 126 pushes the window142 of the housing 140 against the internal wall of the blood vessel.Atheroma, for example, are invaginated by the window 142 in this way(see FIGS. 11 and 12).

The work element 138 aligns adjacent the window 142. When the window 142invaginates atheroma, the work element 138 slides within the housing 140and rotates to cut small pieces of the atheroma. Actuation of the cable134 rotates and axially translates the work element 138 duringoperation.

An inflation manifold 118 secures a rotator assembly 120 to the proximalend 114 of the catheter body 112. The rotator assembly 120 permits thecatheter body 112 to rotate relative to the inflation manifold 118. Atransition element 122 forms over the proximal end 114 of the catheterbody 112 and relieves stress between the catheter body 112 and theinflation manifold 118. A fitting 124 on the inflation manifold 118connects in fluid communication with the with balloon inflation lumen135 in the catheter body 112. A connector 128 on the inflation manifold118 interconnects a perfusion or aspiration source in fluidcommunication with a perfusion lumen of the catheter body 112.

A spline 130 suitable for connection to a motor drive unit (such as thatdisclosed in U.S. Pat. No. 4,771,774, the disclosure of which isincorporated herein by reference) is secured to a drive shaft 132. Thedrive shaft 132 connects to the cable 134. The cable 134 extends throughthe lumen 133 which extends the entire length of the catheter body 112.The cable 134 rotates the work element 138 during operation. An axialadvance lever 136 mounts on the drive shaft 132. The lever 136 permitsmanual axial translation of the cable 134 and work element 138.

A guidewire 146 positions the catheter 110 into an intravascularlocation, for example. Typically, the guidewire 146 first inserts into ablood vessel. The catheter 110 inserts over the guidewire 146. Theguidewire 146 precisely guides the catheter into a desired positionwithin the vascular system of a patient. A lumen 147 in the cable 134and the nose cone 144 provides a path for the guidewire along thelongitudinal axis 137 of the housing 140. The guidewire 146 also passesthrough a lumen (not shown) in the work element 138.

Referring now to FIGS. 3 through 7, a preferred embodiment of theintravascular catheter of the present invention is shown having a workelement 138 and a guiding structure 100. For purposes of the presentinvention, the work element 138 includes an arcuate cutting edge, forexample.

As seen in FIG. 3, the invention includes a housing 140 with slots 150,a slider 152 with at least one pin 156, a work element 138, and a cable134. It will be appreciated that the pin 156 could also be formed in theshape of a spline. The slots 150 align inside the housing 140 inparallel with the longitudinal axis 137 (FIG. 1). The slots 150 extendthrough the housing 140. It should be noted that the slots 150 mayextend only partially through the housing 140. The slots 150 receive thepins 156. The pins 156 slide within the slots 150. In the embodimentillustrated in FIG. 3, two slots 150 are shown, however it is to beunderstood that one or more slots 150 and a corresponding number of pins156 may be used in accordance with the present invention. Additionally,the slots 150 need not be straight and aligned with the axis of thehousing 140. The slots 150 may assume a slightly helical shape forexample.

The pins 156 extend radially from the outer surface of the slider 152.The slider 152 is a cylinder and mounts over a bearing 154 (FIG. 4). Thebearing 154 of the slider 152 mounts on the cable 134. When the cable134 rotates, the slider 152 does not rotate. The slider 152 slides withthe work element 138 and the cable 134.

The slider 152 is a cylinder mounted over a bearing 154 (FIG. 4). Thebearing 154 mounts around cable 134. The interior of the bearing 154 isaffixed to the cable 134 permitting the cable 134 and the interior ofthe bearing 154 to rotate (at high speed if necessary). The slider 152remains rotationally stationary within the housing 140 when the cable134 rotates. The bearing 154 maintains the position of the slider on thecutter torque cable.

The work element 138 is a cylindrical atherectomy cutting blade attachedto the cable 134. Cable 134 rotation and translation respectivelyrotates or translates the work element 138. The slider 152 is alsocoupled to the cable 134 so that it will axially translate therewith.The slider 152 does not rotate when the cable 134 rotates. Thus, theslider 152 remains rotationally stationary with respect to the housing140 even as the cable 134 rotates the work element 138. The slider 152thus guides the work element 138 along the slots 150 with the pins 156.

The preferred embodiment illustrated in FIGS. 3-7 is useful withflexible housings and with rigid housings. Particular geometries anddimensions of the slots 150 and slider 152 and pins 156 may be variedwidely within the scope of the present invention so long as the guidingstructure 100 retains the work element 138 within the housing 140.

Referring now to FIGS. 8 and 9, a preferred embodiment of the pin 156and the slots 150 of the atherectomy catheter 110 of FIG. 3 is shown.The pin 166 and the slot 160 shown in FIG. 8 differ in shape from thepins 156 and slots 150 of FIG. 6. A single pin and slot configuration isshown in FIG. 8 and FIG. 9. FIG. 8 shows a cross sectional view of thehousing 140 of the present invention. FIG. 9 provides a larger scaleview of the slot 160 and the pin 66 in the region demarcated by line9--9 in FIG. 8.

The slot 160 is formed on the inner surface 161 of the housing 140. Thepin 166 extends into the slot 160 partially through the housing 140. Thepin 166 and the slot 160 may also extend fully through the housing 140(see FIG. 3). As shown, the slot 120 tunnels longitudinally within thebody of the housing 140. The slot 160 communicates with the hollowinterior of the housing 140 via a narrow-necked portion 167 of the slot160. The pin 166 forms a "T" shaped cross-section that complements theshape of the narrow-necked portion 167 of the slot 160. The pin 166 isthus free to axially translate within the slot 160. The slot 160radially locks the pin 166 with the housing 140. The slot 160 restrainsthe pin 166 an prevents movement of the pin 166 in the radial directionrelative to the housing 140. A wide variety of pin/slot cross-sectionalgeometries (including, but not limited to a cross, a lollypop, anoblong, a diamond, etc.) provide the same functions of guidance andretention and are within the scope of the present invention. The pin 160can also be a bar having the shape of a railroad track section forexample.

Referring now to FIGS. 10 through 12, another embodiment of the catheterof the present invention is shown. The invention includes housing 140with window 142, catheter body 112, work element 138, cable 134, andcoaxial rod or shaft 170. "BV" generaly indicates a cut away view of ablood vessel. "SM" indicates stenotic material on the interior wall ofthe blood vessel.

FIG. 10 is a cross-sectional side view of the housing 140. The guidingstructure 100 includes a shaft 170. The shaft 170 attaches to the end172 of the nose cone 144. The shaft 170 may be rigid or flexible, solidor hollow. Preferably, a flexible hollow shaft 170 is used with aflexible housing 140. As shown, the shaft 170 aligns coaxially with thehousing 140 and is hollow for circumscribing a guidewire 146 (see FIG.1). The housing is fabricated from a resilient material, such as anelastomeric polymer. The shaft 170 is formed from flexible material, forexample, a tube formed from a superelastic alloy such as nickel-titaniumalloy. A suitable superelastic alloy is commercially available and isfabricated under the trade name Nitinol® by Advanced CardiovascularSystems, Santa Clara, Calif. Tubes formed from superelastic alloysdesirably conform and bend in relation to the bending of the housing140. Such tubes generally provide a smooth arc of curvature which thework element 138 follows.

Use of the shaft 170 guide system provides further advantages in that itfacilitates proximal retraction of the work element 138, as illustratedin FIG. 10 in broken line. The work element 138 can be withdrawnproximally from the housing 140 into the catheter body 112 while thework element 138 remains on the shaft 170. The work element 138 isremoved as an impediment to the flow of blood (or other fluid) from theinterior of the distal portion of the catheter body 112 through thehousing 140. The catheter body 112 is adapted to receive the workelement 140 by flaring the distal end 116 of catheter body 112 over theproximal end of the housing 140, as illustrated. The distal end 116 canthen be secured to the proximal end of the housing 140 using aconnecting ring 76. Bypass perfusion ports 178 are provided within thedistal portion of the catheter body 112 and proximal to the distal endof the catheter body 112, as described in more detail in copending U.S.application Ser. No. 08/236,485 filed Apr. 29, 1994 (attorney docketnumber DEVI 1464), and entitled "Catheter with Perfusion System", thefull disclosure of which is incorporated herein by reference.

FIGS. 11 and 12 illustrate operation of an atherectomy catheter withinthe scope of the present embodiment. In FIG. 11 the housing 140 islocated within a curved region of blood vessel BV. Stenotic material SMis located on the outer radius of the curve so that the housing 140 islocated with housing window 142 directed radially outward. It will beappreciated that, with the housing 140 in such a configuration, theunguided work element 138 has a tendency to travel outward through thewindow 142 and into the wall of the blood vessel BV. Such a trajectoryis not desirable since it can damage the blood vessel wall. Shaft 170defines a curved travel path which maintains the work element 138generally within the housing 140 and inhibits undesirable deviation ofthe cutter into the blood vessel wall.

In FIG. 12, use of an atherectomy catheter in removal of stenoticmaterial SM along the inside radius of curvature of a blood vessel BV isillustrated. When the housing window 142 is on the inside radius ofcurvature, the work element 138 tends to cut into the inside wall of thehousing 140, rather than cutting along the optimal path for removal ofstenotic material SM. The shaft 170 again defines the proper travel pathfor the work element 138 so that it avoids cutting into the housing 140and is properly disposed to remove the stenotic material SM, asillustrated.

Referring now to FIGS. 13 and 14, an embodiment of the catheter with aguiding structure 100 is illustrated. The embodiment includes housing140 formed with a window 142, a work element 138, a cable 134, a ribbon180, and a slider 152.

The housing includes a keyway 185. The work element 138 includes aslider 152 having an outer surface 163 with an extension 187. Theextension 187 defines guide hole 195 which receives the ribbon 180. Theslider 152 holds the work element 138 in a desired position with respectto the housing 140.

The extension 187 slides along the keyway 185. The ribbon 180 holds thekeyway 185 and the extension 187 together. The ribbon 180 extends fromthe proximal end 139 of the housing 140 to the distal end 141 of thehousing 140. The holes 193 formed in the housing 140 hold each end ofthe ribbon 180. The ribbon 180 extends through the guide hole 195 formedin the housing 140 to lock the work element 138 against the housing 140.

FIG. 13 is a cross-sectional view of the housing FIG. 14 is a crosssectional view of the housing in FIG. 13 as seen along the line 14--14.The ribbon 180 is a shaft with a flat geometry and is secured to thedistal end of housing 140, typically being attached to a ring 182 whichsecures the nose cone 144 to the housing. The ribbon 180 has a widththat is at least 1.5 times its thickness, preferably at least 3 timesits thickness. The ribbon 180 is metallic, and preferably made from thefamily of metals known as superelastic alloys, and most preferablyNitinol®.

Referring now to FIGS. 15-18 still another embodiment of the catheterwith guiding structure 100 is illustrated. The housing 140 has an outersurface 109 with a smooth exterior portion 191. The work element 138 isformed with an annular depression 192. The guiding structure 100includes a band 190.

FIG. 15 is a side view illustrating the outer surface 183 of the housing140 and the guiding structure 100. The band 190 couples the work element138 with outer surface 109 of the housing 140. An annular depression 192forms in the housing 140. The annular depression 192 accepts the band190. The band 190 surrounds the outer surface 109 of the housing 140over the smooth portion 191 of the housing 140.

In FIG. 16, the work element attaches to a protective member 193. Theannular depression 192, work element 138, protective member 193 and theband 190 are shown.

FIGS. 17 and 18 are cross-sectional views through the lines 17--17 and18--18 respectively, shown in FIG. 15. The work element 138 rotates. Theband 190 remains rotationally stationary. The band 190 flexes andtranslates axially when the work element 138 moves. The band 190 isfabricated from a metal, or a lubricious polymer, such as nylon, orpolymers and copolymers of tetrafluoroethylene, or the like. Theprotective member 193 attaches to the housing 140 between the band 190and the balloon 126 to prevent damage to the balloon 126 when the band190 slides on the housing 140.

As described, the present invention is especially useful in atherectomyapplications where the work element 138 is a rotating or rotationallyoscillating curing blade, and is operated by simultaneously rotationallytranslating and axially translating the blade 138 past the side window142 in the housing 140 in order to sever and remove stenotic materialfrom an area of interest, e.g. a stenosed region of blood vessel.However, other embodiments utilizing the guiding structures 100described above are contemplated and are within the scope of the presentinvention. Examples of intravascular catheters containing alternativework elements 138 include, but are not limited to, cutting blades forperforming atherectomy procedures, heated elements for performingthermal ablation, electrodes for performing electrosurgical cutting andcauterizing, abrasive elements for performing mechanical ablation,optical wave guides for performing laser ablation, ultrasonictransducers for imaging or ablation, fiber optical elements forvisualization and imaging, and the like.

In each case, the cable 134 is appropriate to facilitate operation ofthe work element 138. For example, a cutting blade utilizes a cable,thermal ablators utilize electrical wires, laser ablators utilizeoptical elements, etc. Work element connectors appropriate for each workelement are known to those skilled in the art.

It will be appreciated that intravascular introduction of a catheter,particularly into coronary arteries, frequently requires the catheter topass through very tight turns and bends resulting from the tortuosity ofthe blood vessels. The guiding structure 100 of the present inventionfacilitates axial advancement of the cutting blade while the cutterhousing is positioned in such tortuous regions, particularly byinhibiting loss of the cutting blade from flexible housings through thework window. The advantages of the present invention, however, alsoextend to the use of rigid cutter housings in less tortuous regions,where the cutter guide system of the present invention allows for theuse of very wide work windows where, in the absence of the guide, thecutter would be at risk of escaping from the housing. Wider work windowsare desirable for cutting, ablation, and viewing or imaging of largerregions of the vascular wall.

Fixed axial registration of the guiding member and housing help assurethat the guiding member remains properly aligned within the housing. By"fixed", it is meant that the guiding member will not translate axiallyrelative to the housing, although some degree of radial movement will beacceptable and, in some cases, even necessary. Axial paths defined byslots and channels which are formed in or on the interior surface of thehousing will necessarily be fixed relative to the housing. Elongatedmembers comprising shafts, bands and the like, are attached to thehousing at least one end, preferably both ends. Such attachment may bedirect, i.e., formed directly between the guiding member and a surfaceof the housing, or may be indirect, i.e., made through a separatecomponent of the catheter which is itself fixed relative to the housing,e.g., a nose cone, a housing connection ring, a portion of the catheterbody, or the like. Such separately formed guiding members may, ofcourse, directly or indirectly attach to the housing at more than onelocation.

Moveable guidewires have been used as a guiding structure inintravascular catheters. However, movable guidewires (which are free toaxially translate relative to the housing) will often become axiallymisaligned within the housing as the catheter is advanced thereover.That is, the movable guidewire can be axially collapsed as the catheteris advanced, causing a pronounced lateral deflection within the interiorof the housing. Such lateral deflection is unacceptable to define theaxial path for the work element to track. The guiding structure 100sdisclosed in the present invention solve this problem in that theydefine an axial path that is fixed relative to the housing.

Materials

As described, the housing may be rigid or flexible, typically beingformed from a metal, such as surgical stainless steel, organic polymerssuch as polyacetal, reinforced polymers such as graphite filledpolyesters and ceramics. A rigid housing has a generally continuousconstruction, usually composed of a metal or rigid plastic, includingthe side window but free from other spacings or voids intended toenhance bendability. A flexible housing is usually formed from resilientmaterials, such as polyurethanes, elastomeric polyesters and the like,or if formed from metal or other rigid (non-resilient) material willinclude spacings or voids which are intended to facilitate bending. Theconstructions of particular flexible housings are illustrated in U.S.Pat. No. 4,781,186 and U.S. Pat. No. 5,226,909 the disclosures of whichare incorporated herein by reference.

The slots formed in the housing may penetrate entirely through thehousing wall, or may only partially penetrate the wall. Only a singleslot may be formed, in which case it is desirable that the slot havecross-sectional geometry which locks in the coupling means, e.g., aT-shaped profile as illustrated in FIG. 8. In the case of multipleslots, it is less important that the coupling element be locked in.Coaxial shafts and off-set bands used as a guiding member may be rigidor flexible, depending primarily on the nature of the housing. Flexibletracking elements are preferred in flexible housings, but can also beused in rigid housings.

The elongated catheter body of the present invention typically comprisesa flexible tube which can be similar in construction to a wide varietyof intravascular catheters, the type which are well known in the art.The flexible tube will have a proximal end and a distal end and at leastone lumen extending therebetween. The tube may be formed by extrusion ofan organic polymer, typically a thermoplastic, such as nylon,polyurethane, polyethylene terephthalate (PET), polyvinylchloride (PVC),polyethylene, and the like. The tubes so formed may be reinforced orunreinforced, usually being reinforced by a metal braid which islaminated with the polymeric material. Use of the metal braidreinforcement layer is desirable since it facilitates torquing andpositioning of the cutter housing, as described in more detail below.The catheter body will typically have a length from about 40 cm to 200cm, with shorter catheters in the range from abut 40 cm to 120 cm beingused for peripheral applications and longer catheters in the range fromabout 100 cm to 200 cm being used for coronary applications. Thediameter of the catheter body may also vary, with smaller diametercatheters in the range from about 3 French (F; 1 F=0.33 mm) to 6 F, forcoronary applications and a diameter from 3 F to 11 F for peripheralapplications.

When the catheter is an atherectomy catheter, the cutter housing definesan open or hollow interior volume to receive stenotic material whichpenetrates or passes through the side window. The cutting blade isadvanced past the window severing the stenotic material and advancingthe severed atheroma toward the distal end of the housing. The distalend of the housing will typically be open and connected to a nose coneso that the severed stenotic material can be moved into the nose conefor storage.

In certain embodiments the cutter defines a cup-shaped cutting bladewhich is rotated (or rotationally oscillated) and advanced to sever theatheroma and urge the atheroma in a forward direction. Such cuttingblades are illustrated in U.S. Pat. Nos. 4,979,951 and Reissue 33,569,the disclosures of which have previously been incorporated herein byreference.

The length of the cutter housing will depend primarily on the desiredlength of stenotic material to be severed, with the limitation thatlonger housings are more difficult to manipulate through the vascularsystem. Typically, the length of the housing is 5 mm to 40 mm. Forcoronary applications, the housing length will generally be at theshorter end of the range, usually being from about 8 mm to 17 mm. Thehousing diameter will generally correspond to the diameter of theflexible tube, i.e. usually being in the range from about 3 F to 11 F.

The cutter window within the housing typically extends over at leasthalf of the housing length, and in other embodiments the cutter windowextends over at least three-quarters of the housing length. It will beappreciated that it is desirable to maximize the length of the housingin order to increase the amount of stenotic material which can beremoved in a single pass of the cutting blade. It is also desirable toincrease the width of the housing window for the same reason. The cutterguide system of the present invention is particularly advantageous sinceit permits cutter windows having a greater width that was generallypossible with previous atherectomy catheter designs. For cylindricalhousings, the cutter width will typically subtend an arc of at least115°, preferably subtending an are of at least 130°, and may subtend anarc of 180°, or greater. The use of such wide housing windows ispossible only because the guide system of the present invention willcontain the cutting blade generally within the interior of the housing,even when the housing is subjected to bending and other deformationstresses which might otherwise cause the cutter to escape from thehousing through the housing window.

While the foregoing detailed description has described a preferredembodiment of the intravascular catheter, it is to be understood thatthe above description is illustrative only and not limiting of thedisclosed invention. Particularly, the specific details of the geometryof slots and pins can differ from those illustrated and described solong as the guidance system guides and retains the work element withinthe housing. The invention is to be limited only by the claims set forthbelow.

What is claimed is:
 1. An assembly for use with an intravascularcatheter having a proximal end and a distal end and a cable,comprising:a housing attachable to the distal end of the intravascularcatheter, the housing including an axis and a window and an innersurface having at least one slot formed parallel to the axis of thehousing; a work element slidably attached to the housing adjacent thewindow, the work element being fixed on the cable, the work elementsliding and rotating when actuated by the cable; and a guiding structureattached to the housing and to the work element to lock the work elementin juxtaposition with the housing and prevent extension of the workelement through the window, the guiding structure including at least onepin extending radially from the work element, the pin engaging the slotto permit the work element to slide along a desired path within thehousing, whereby the work element is locked in juxtaposition with thehousing and extension of the work element through the window isprevented.
 2. An assembly as set forth in claim 1 wherein the innersurface of the housing has a single slot, the guiding structure has asingle pin, the pin has a "T" shaped cross section, the slot includes anarrow necked portion which conforms to the shape of the pin, the slotrestrains the pin from radial movement with respect to the housing. 3.An assembly for use with an intravascular catheter having a proximal endand a distal end and a cable comprising:a housing, attachable to thedistal end of the intravascular catheter, defining an axis and having awindow and a distal end; a nose cone attached to the distal end of thehousing; a work element, slidably attached to the housing adjacent thewindow and fixed on the cable and capable of sliding and rotating whenactuated by the cable; and a guiding structure, attached to the housingand to the work element to lock the work element in juxtaposition withthe housing and to prevent the extension of the work element through thewindow, including a resilient shaft held coaxial with the housing at thenosecone and at the distal end of the intravascular catheter, the shaftbeing coaxial with the work element.
 4. A device as set forth in claim 3wherein the shaft is hollow for circumscribing a guidewire.
 5. A deviceas set forth in claim 3 wherein the shaft is fabricated from asuperelastic alloy.
 6. An assembly for use with an intravascularcatheter having a proximal end and a distal end and a cable comprising:ahousing, attachable to the distal end of the intravascular catheter anddefining an axis and including a window and a smooth exterior portion; awork element, slidably attached to the housing adjacent the window andfixed on the cable and capable of sliding and rotating when actuated bythe cable, including an outer surface having an annular depression; aguiding structure, attached to the housing and to the work element tolock the work element in juxtaposition with the housing and to preventthe extension of the work element through the window, including a bandattached about the smooth exterior portion of the housing and about theannular depression of the work element, the band sliding with the workelement along the housing to hold the work element and the housingtogether.
 7. A device as set forth in claim 6 wherein the assemblyincludes a balloon affixed to the housing, the guiding structureincludes a protective member which covers a portion of the band toprotect the balloon from the band.
 8. An intravascular catheter as setforth in claim 7 wherein the work element defines a tunnel along theaxis thereof, the guiding structure comprises a shaft disposed withinthe hollow interior of the housing and connected thereto, the shaftpassing through a tunnel within the work element such that the workelement is slidably translatable along the shaft, the shaft aligns withthe axis of the housing.
 9. An intravascular catheter as set forth inclaim 7, the housing having an external surface, the guiding structurecomprising the external surface of the housing and a band which slidablycircumscribes the housing and the work element disposed therein.
 10. Anintravascular catheter as set forth in claim 9 wherein the band isflexible.
 11. An intravascular catheter as set forth in claim 9, whereinthe work element comprises a cutting blade having an outercircumference, an annular depression circumscribes the outercircumference of the cutting blade and the band is received in theannular depression.
 12. An intravascular catheter as set forth in claim7 wherein the distal end of the catheter body defines perfusion ports.13. An intravascular catheter as set forth in claim 7 wherein the workelement is a cylindrical atherectomy cutting blade with an outercircumference, the cutting blade being axially and rotationallytranslatable, and the cable being an axially and rotationallytranslatable cable, whereby translation of the cable results intranslation of the cutting blade.
 14. An intravascular catheter as setforth in claim 7 wherein the housing includes a lateral side and aninflatable balloon attached to the housing on the lateral side wherebyinflation of the balloon within a blood vessel displaces the housingtoward a side of the blood vessel.
 15. An intravascular cathetercomprising:a catheter body having a proximal end, a distal end and alumen therebetween; a housing having a cylindrical body, a longitudinalaxis, an internal surface, an external surface defining a window, and anopen proximal end secured to the distal end of the catheter body, thehousing is flexible and defines a hollow interior; a work elementdisposed within the housing and having a proximal end; a cable alignedfor sliding within the lumen of the catheter body; a connector forsecuring the work element to the cable, the connector being attached tothe proximal end of the work element; and a guiding structure affixed tothe housing and connected to the work element to slide the work elementalong the axis of the housing, the guiding structure including a slotthrough the internal surface of the housing, a slider attached to thework element, and a pin attached to the slider and inserted within theslot; whereby the work element is retained within the housing duringinsertion of the catheter within a blood vessel and during axialtranslation of the work element along the axial path of the guidingstructure.
 16. An intravascular catheter comprising:a catheter bodyhaving a proximal end, a distal end and a lumen therebetween; a flexiblehousing which defines a hollow interior, having a cylindrical body, anopen proximal end secured to the distal end of the catheter body, alongitudinal axis, an external surface defining a window, and aninternal surface; a work element disposed within the housing and havinga proximal end; a cable aligned for sliding within the lumen of thecatheter body; a connector for securing the work element to the cable,the connector being attached to the proximal end of the work element;and a guiding structure, affixed to the housing and connected to thework element to slide the work element along the axis of the housing,including at least one slot in the internal surface of the housingdefining an axial tunnel within the body of the housing andcommunicating with the hollow interior of the housing, and furtherincluding a slider rotatably attached to the work element, the sliderhaving at least one pin extending into the slot in the housing, wherebythe work element is retained within the housing during insertion of thecatheter within a blood vessel and during axial translation of the workelement along the axial path of the guiding structure.
 17. Anintravascular catheter as set forth in claim 16 wherein the work elementdefines a tunnel along the axis thereof, the guiding structure comprisesa shaft disposed within the hollow interior of the housing, the shaftpasses through the tunnel within the work element such that the workelement is slidably translatable along the shaft, the shaft beingcoaxial with the axis of the housing.
 18. An intravascular catheter asset forth in claim 16 wherein the housing has a distal end including ashaft, the shaft is resilient, the shaft being attached to the housingat the proximal and distal ends of the housing, the shaft having a flatribbon geometry.
 19. An assembly for use with an intravascular catheterhaving a proximal end and a distal end and a cable, comprising:ahousing, attachable to the distal end of the intravascular catheter andincluding a window, an inner surface, a proximal end, and a distal end,the proximal and distal ends each having a hole therein; a work element,slidably attached to the housing adjacent the window, fixed on thecable, and capable of sliding and rotating when actuated by the cable; aguiding structure, attached to the housing and to the work element tolock the work element in juxtaposition with the housing and to preventthe extension of the work element through the window, including a keywaydefined in the inner surface of the housing, a slider rotatably attachedabout the axis of rotation of the work element and holding the workelement in a desired position with respect to the housing, an extensiondefined by an outer surface of the slider and further defining a guidehole, the extension sliding in the keyway, and a ribbon, extendingbetween the holes in the proximal and distal ends of the housing andheld in the housing thereby, passing through the guide hole in theextension of the slider to hold the extension in the keyway and to lockthe work element in the housing, whereby the work element is retainedwithin the housing during insertion of the catheter within a bloodvessel and during axial translation of the work element along the axialpath of the guiding structure.